Collapsible tapered carton



-Aug. 28, 1956 'r. J. BRUEHL ETAL COLLAPSIBLE TAPERED CARTON 3 Sheets-Sheet 1 Filed June 9, 1955 Q INVENTORS. "THOMAS J; BRUEHL BY HOWARD N- HOVLAND GEORGE E. VERHAGE UWLA vT. J- BRUEHL EI'AL COLLAPSIBLE TAPERED CARTON Aug. 28, 1956 3 SheetsSheet 3 Filed June 9, 1955 INVENTORS.

f H MAS I BRUEHL HOWARD N. HOVLAND BY GEORGE E VERHAGE ATTYS.

2,760,709 COLLAPSIBLE TAPERED CARTON Thomas J. Bruehl, Menasha, Howard N. Hovland, Appleton, and George E. Verhage, Neenah, Wis., assignors to Marathon Corporation, Menasha, Wis, a corporation of Wisconsin Application June 9, 1955, Serial No. 514,212

4 Claims. (CL 229-39 Referring first to Figure 1, the carton blank (ordinarily paperboard) includes side walls 1, 2, 3, and 4 hingedly connected along score lines 5, 6 and 7, and a glue flap 8 hinged to a side edge of Wall 1 along score line 9. The free side edge of Wall 4 is indicated by numeral 31. Top closure flaps 10, 11, 12 and 13 are hinged to the top edges of side Walls along score lines 14, 15, 16 and 17. Along the remote edge of flap 10 a male locking member 18 is formed and a cooperating female locking slit 19 is formed in flap 12, in the conventional manner.

Bottom closure flaps 20, 21, 22 and 23 are hinged to the bottom edges of the side walls along score lines 24, 25, 26 and 27, flaps 21 and 23 being divided into two parts by diagonal score or perforation lines 28. The remote portions of flaps 21 and 23 have cut outs or notches 29 formed therein for a purpose to be described later in matically move to close the bottom end of the carton.

Cartons of this sort are widely used in the packaging of many commodities, and have achieved particular popu+ larity in the packaging of ice cream. Forsuch purpose, where the appearance of the packaging medium is of great consequence in determining acceptanceland sale of the cartoned product, it is important that the package or carton incorporate all possible features to render it at tractive.

It has thus far been found impractical to manufacture a tapered automatic bottom carton of rectangular crosssection in which the carton has a regular, uniform and substantially symmetrical appearance. That is, it has been impractical to manufacture such a carton wherein opposite side walls of the carton are identical to each other and are inclined at the same angle with respect to the bottom of t the carton, and the side edges of opposite wall are all inclined at the same angle with respect to the bottom. The failure to have these characteristics obviously detracts from the appearance of the erected carton. This failure has been due principally to the impossibility heretofore of manufacturing such cartons of various dimensions in accordance with a regular or standard procedure.

Accordingly, it is the principal object of this invention to provide a rectangular cross-section, tapered, automatic'bottom carton having the desired appearance above set forth, and to provide a procedure whereby such cartons may be manufactured regardless of particular linear dimensions desired.

In describing our invention, reference will be had to the attached drawings, in which Figure l -is a plan view of a blank for a carton incorporating our invention,

Figure 2 is a plan view, partially cut away, similar to Figure l, but with certain portions of the blank in folded condition and with adhesive applied thereto,

Figure 3 is a bottom elevation of our carton in glued Figure 8 is a plan view similar to Figure 7, but with two of the side walls overlying the other two walls, and;

Figure 9 is a plan view similar to Figure 8, but with corrective factors applied to produce carton side walls in accordance with our invention.

detail.

With additional reference to Figure 2, in the initial step of forming the carton from a blank, bottom flap 20, 21, 22 and 23 are folded upwardly to overlie the Walls to which they are hinged. The portions of flaps 21 and 23 outward of perforation lines 28 are then reversely folded and a suitable conventional adhesive applied to the exposed surface of those flap portions and also to the upper surface of glue flap 8, this adhesive being indicated by reference numeral 30. Wall 4, carrying with it flap 23, is then folded about score line 7 to overlie wall 3, thus bringing the adhesive-coated portion of flap 23 into adhering contact with flap 22. Wall 1, carrying with it flaps 8 and 20, is then folded to overlie wall 2, bringing flap 20 into adhering contact with the exposed adhesive-coated portion of flap 21 and the adhesive-coated surface of flap 8 into adhering contact with wall 4 adjacent the free edge thereof. The thus-formed collapsed carton is briefly re strained in this essentially folded condition until the ad hesive 30 has had time to form a secure bond between the related elements. I

The collapsed carton thus formed may be erected by pushing inwardly upon opposed corners of the carton, as represented by score line 5 and 7, with the result illustrated in an intermediate stage in Figure 3 and in the final stage in Figure 4. The bottom flaps are so proportioned and arranged that as the erecting process is carried out there results a positive and interlocking engagement of the notches 29 of flaps 21 and 23, to prevent collapse of the carton from the erected position shown in Figure 4;

and flap 22, which is of size to substantially completely close the bottom of the carton, lies innermost of the bottom flaps, to provide a substantially leakproof construction.

Figure 5 shows What might be either carton side wall 1 or wall 3, since in our invention these twowalls are identical. The top and bottom edges of side walls 1 and 3 are parallel and the side edges have the same angular relationship to the bottom edge. Figure 6 represents either side wall 2 or 4, since these two walls are identical; the top and bottom edges are parallel, and the side edges have the same angular relationship to the bottom edge. However, the angular relationship of the side edges of walls 1 and 3 to their bottom edge is different from the angular relationship of the side edges of walls 2 and 4 to the bottom of those walls, as will later be described in detail.

Figure 7 represents a blank layout of the walls only of a carton, in which the side edges 109, 105, 106, 107

an angle plus an angular increment a, these angular increments in Figure 7, although equal, being noted as 01, 112, a3, a4, as, as, at, and as. The walls of this carton 103 and 104 in Figure 7, and correspond respectively to walls 1, 2, 3 and 4 in Figure 1, and the other elements similarly correspond.

With additional reference to Figure 8, when walls 104 and 103 arefolded about edge 106 to overlie walls 101 and 102, it will be observed that edges 109 and 131 fail to coincide, for geometrical reasons which brief consideration will make apparent. While the exact folding technique employed here is different from that described in connection with Figures 1 and 2, the result is obviously the same and this method more clearly illustrates the problem. With this failure of coincidence, it is obviously impossible to make a carton from the blank of Figure 7, and it will be clear that this impossibility cannot be removed by variation in the method of folding. The conclusion is necessarily reached that if there is to be a tapered carton which in cross-section is rectangular and other than square, it will be impossible to have the side walls bear equal angular relationship to the bottom of the carton. This invention presents a procedure for determining the angular relationship that must be utilized to bring into coincidence side edges 109 and 131 and thus presents a carton which can be manufactured for the intended purpose.

With further reference to Figures 7 and 8, the solution to this problem, which comprises the heart of the invention, is approached by ascertaining that the initial step in obtaining coincidence of side edges 109 and 131 involves moving each of points (intersection of edges 109 and L1) and e (intersection of edges 131 and L1) half way toward each other, to meet at point f. In order to present 7 an attractive and regularly shaped carton, it is necessarily kept in mind that opposed side walls must in final condition be identical to each other and with their side edges equally inclined to the bottom of the carton.

With point g (intersection of edges 106, W1 and L2) as a center, an arc is drawn connecting points at and e, with point i at its mid-point. The equal radius lines connecting center g with points d, f and e are denoted as N1, N2 and Na.

The solution of the problem of the equal angular distances through which points at and e must be moved to coincide at 1, which angles are identified as on, and a2, may take the following form:

2a arcos -arcos 204 arcos Referring to Figures 7, 8 and 9, the application of angle a to the assumed carton blank involves usingedge or score line 106 as a fixed base line. If angle a is applied as a negative or subtractive increment to angle as, it will be apparent that the blank at point e will be raised to position i. Conversely, if u is applied as a positive or additive increment to angle as, point d will be lowered to position 1. Negative application of a to angle as will cancel positive application to as, and similarly with re: spect tovpositive application to as and negative to at, insofar as movement of the wall-bottom edges is concerned. It is also-readily observed that negative application of a to as coupled with positive application to (11, results solely in creating coincidence, of. edges 109 and 131. The resulting construction is as shown in Figure 9 in full lines, the phantom lines showing the initial construction of Figure 8.

In summary, the above application of angular increment on to the assumed angular disposition of the side Wall side edges relative to the bottom edges resultsiii increasing the angle as to the longer side walls (101 and 103) and by the same amount decreasing the angle as to the shorter side walls (102 and 104). Thus, the opposite side walls are identical to each other, each side edge of opposite side walls lies at the same-angle relative to the bottom edge, and the erected carton will be of rectangular cross-section. An attractive and symmetrical elevational appearance of the carton necessarily follows.

It-will'now also be clear that our end product is a carton which can in fact be manufactured. Since edges 109 and 131 coincide,ta glue tab or panel such as 8 (Figure, 1) .can be applied to either of walls 101 and 104 for adhesion to the other of those walls, and bottom and top flaps similarly'provided.

To. achieve. the desired volume or capacity of the finished carton it is only necessary to determine by simple mathematical formulae the height of the carton necessary in relation to the now known cross-section. 1

Reflection now reveals that through the help of a simple mathematical formula we can provide an attractive carton as previously indicated, the only requirements being initial determination of base lengths of the side walls and assumption of the average of the angles at which we i wish the side edges of the Walls to be disposed relative to the base.

As an example of the use of our formula, we can assume that it is desired to manufacture a carton in which the base (L) of one pair of opposed side walls is to be 1 three. inches, the base (W) of the other pair of two inches,

and the average assumed 'side edge angle 105 (=+l50=90.+a).

a a} arcos Applying these values to Figures 7 and 8, with result 'arcos arcos 8,1005

= BIIGGS arcos arcos shown in Figure 9, edge-defining score lines 109, 105, 106, 1437 and 131 lie at an angle a+90+a with respect to the side wall bottom edges, while these lines be at an angle a+90a with respect to these edges.

It will become apparent that the solution 'of the principal problem might be approached in other ways, but ending with the same result, without departure from the basic elements of this invention. For example, with the same known, assumed quantities as used in the preceding solution,

By substitution,

L sin R i W sin R) N arcs n W sin 2a arcs1n-- VL +W +2LW cos 2a Again, if we assess values L=3, W=2, a=15, this method results in the solution cc=3 04, as before.

Thus our invention involves not only the use of a definite formula, but also separately the employment of a method whereby adjustments to unworkable assumed carton dimensions are made in a set pattern to provide a perfectly workable and attractive carton.

Brief reflection will make obvious the fact that the invention here involved is independent of the method of folding the carton blank, and is equally applicable to carton blanks folded as in Figure l and as in Figure 8.

Having now described and illustrated our invention, it must be understood that no limitations are to be applied except as set forth in the appended claims.

We claim:

1. A collapsible four walled carton having an automatic bottom, the top and bottom of the carton being co-parallel, the walls of the carton being inclined with respect to the bottom, opposed walls being identical and inclined at the same angle with respect to the bottom, adjacent walls being inclined at different angles with respect to the bottom, the carton in cross-section being rectangular a=arcsin sin -(arcsin =%(arcsin and other than square, the carton having given length and width dimensions of the bottom and an assumed height, the side edges of one opposed pair of walls being inclined with respect to the bottom at an angle +l+0$ and the side edges of the other pair of opposed walls being inclined with respect to the bottom by an angle 90-|-a-u, in which a is an assumed angular increment by which said side edges are on the average desired to vary from perpendicular to the bottom and a: arcos L and W being respectively the given length and width dimensions of the bottom.

2. A carton according to claim 1, further characterized by the fact that the side edges inclined at the angle 90+w+u are the side edges of the side walls having the greater bottom dimension.

3. A collapsible four-walled carton having an automatic bottom, the top and bottom of the carton being coparallel, the walls of the carton being inclined with re spect to the bottom, opposed walls being identical and inclined at the same angle with respect to the bottom, adjacent walls being inclined at different angles with respect to the bottom, the carton in cross-section being rectangular and other than square, the carton having given length and width dimensions of the bottom and an assumed height, the side edges of one opposed pair of walls being inclined with respect to the bottom at an angle 90+a+a and the side edges of the other pair of opposed walls being inclined with respect to the bottom by an angle 90+aa, in which a is an assumed angular increment by which said side edges are on the average desired to vary from perpendicular to the bottom and arcos a: arcsin 90+zz+a are the side edges of the side walls having the greater bottom dimension.

No references cited. 

